Human skin consists of three basic layers: the epidermis, the dermis and the hypodermis. The outer layer of skin is the epidermis. Epidermis is the thinnest of the layers and contains mainly stratified squamous epithelium of which the outer side keratinizes and ensures coverage. The inner side contains a pigment. The middle layer of skin is the dermis. Dermis consists mainly of the collagen, elastic and reticular fibers. The bottom layer of skin is the hypodermis. The hypodermis is formed mainly by blood vessels, lymphatic vessels, nerve fibers, fibroblasts and in particular adipocytes.
Increases in average life expectancy, obesity, unhealthy lifestyles, genetic predispositions and other factors may cause aesthetically undesirable appearance of the skin. The undesirable appearance of the skin may manifest itself by excessive volume of fat, cellulite, skin laxity, loss of elasticity, loss of firmness, etc. The undesirable appearance is caused mainly by the excessive volume of fat cells, weakness and/or break down of collagen, elastin fibers or other known reasons.
Aesthetic devices delivering an electromagnetic energy have recently been developed and various invasive and contact approaches solving undesirable skin appearance are known. However invasive methods require long recovery time and place high time and skill demands on practitioners. They also involve strict requirements for a sterile environment and biocompatibility. Invasive treatments can be painful and traumatic. Moreover there is always risk of infection and inflammation of the treated tissue.
Non-invasive methods which still require contact with the patient also must fulfill high sterility and biocompatibility requirements. The operator of a contact device must disinfect or replace an individual contact part of the applicator before or during the application, which consumes time of the operator.
Non-contact treatment eliminates these disadvantages since it reduces the time required for disinfection, and replacement of an individual contact part or manipulation along the treated area. Since the devices do not contact with the patient there is no need for biocompatible materials.
Non-contact radiofrequency therapy can be used for reduction of volume and number of fat cells in the hypodermis, removal of cellulite, body contouring, neoelastogenesis and neocollagenesis. Methods of these therapies are described for example in US patent application number 2014/0249609, incorporated herein by reference.
However, engineering challenges remain in trying to optimize the amount of energy delivered to the skin of the patient during contactless radio frequency therapy. Current devices for contactless radiofrequency therapy present the values measured at the HF generator as the real output values which are directed to patient, and calculate from these values the energy delivered during therapy.
However, a considerable amount of RF energy is unintentionally converted to other forms of energy in the devices for contactless skin treatment, due to parasitic effects, transformation losses, resistivity of various conductive materials, etc., which limits the amount of output energy.
The actual therapeutic energy delivered to the patient varies depending on the impedance of the patient and distance between patient and the radiofrequency electrode. Since the patient is not in direct contact with a source of RF signal, the distance between patient and the radio frequency electrode during the time therapy is changing. This may be caused either by biological rhythms such as breathing and heartbeat which cause movements of the treated tissue or movements during the duration of therapy. The therapeutic energy delivered may be insufficient due to low electrical resistance of some patients, and distance changes leading to creation of electric potential in thousands of Volts on each symmetrical branch of the non-contact device.
Accordingly, there is need for improvement of the devices for contactless skin treatment so as to control the input power in order to obtain a continuous heating of the target skin and human tissue and to continuously deliver an optimum amount of energy into the skin of the patient without causing any injury to the upper or inner layer of the skin.